The present invention relates to a process for the production of carboxylic acid esters by reacting olefins with carboxylic acids. It is known that the reaction of olefins and carboxylic acids results in the formation of the corresponding carboxylic acid esters. This reaction is usually performed in the presence of liquid catalysts, e.g., (1) strong acid catalysts, such as sulfuric acid and a combination of boron trifluoride (BF.sub.3) and hydrogen fluoride (HF), and (2) media containing the free heteropolyacid of phosphomolybdic acid or phosphotungstic acid, and water.
The catalysts listed in (1) above, however, have the serious defect that they cause corrosion of apparatus. The catalysts listed in (2) above also have disadvantages. They produce alcohols together with the desired carboxylic acid esters. When ethylene is used as a starting material, the ethyl ester cannot be prepared since it is usually converted into a sec-butylester. The conventional methods using the aforedescribed catalysts are disadvantageous in that because the catalysts are liquid, the methods require specific equipment for the separation of products from the catalysts, and for purification of products, etc.
In order to remove the above disadvantages, a method using various ion exchange resins has been proposed. This method suffers from disadvantages in that it is not possible to increase the temperature and pressure to higher levels in order to increase the yield, because the ion exchange resin catalysts are seriously deterioriated by heat, and in that the reproduction of the catalyst is difficult.
It has also been proposed to use Y-type zeolite and mordenite zeolite as solid acid catalysts. These zeolite catalysts, however, have the defect that when reacting ethylene and propylene, the rate of reaction is very small although it is observed that they exhibit high reactivity to isobutylene. In the production of carboxylic acid esters by the use of the zeolite catalysts, it is known that the reactivity is determined by the number of carbon atoms and structure of the olefin used. The influence of the carboxylic acid on the reactivity is small. It is, therefore, apparent that when the olefin used is isotubylene, the reaction proceeds easily, whereas when the olefin used is, in particular, ethylene, the reaction proceeds with difficulty since the reaction of an olefin with a carboxylic acid becomes more difficult as the number of carbon atoms of the olefin is decreased.